It is well known that sheets of glass, for example, glass for the automotive industry, mirrors, etc. have been cut in keeping with the desired shape, which therefore has to have its edges polished, both for eliminating any possible burrs as well for removing small peripheral fractures that might cause the glass to shatter during the next process that it will be subjected to such as tempering, bending, etc.
Regularly, the edges of the sheets of glass are subjected to a process known as "machining the edge with polishing", which consists of passing a fine grain polisher or a diamond wheel through the length of the edge of the sheet or glass plate several times. The edge of the sheet has to be maintained humid in order to cool the grinding stone, as well as to prevent the raising of glass dust during the grinding or polishing of the sheet.
In order to maintain the grinding or polishing stone wet, it is necessary that there be a continuous flow of water to cool the grinding or polishing wheel. However, the main problem resides in that with this type of grinders, the flow of water drains over the edge of the sheet of glass, staining it with all of the dust that has been ground off.
Another problem that presents itself in the grinding or polishing used for sheets of glass is that on some occasions the water does not fall directly onto the grindstone, thus provoking the edge of the sheet of glass to get burnt.
In order to resolve the above, after the sheets of glass have been polished, an operator has to clean them in order to remove any residual that may be left after the polishing operation. However, in some cases, the sheet of glass had already been damaged (by spots or burnt places), and because of this it has to be discarded because it does not comply with the quality standards that are required by the automotive industry.
At present there are already polishing machines for polishing the edge of a sheet of glass, for example, U.S. Pat. No. 4,426,811, of Rudolf Eckardt et al, which refers to a method of grinding glass sheets whose edges are polygons that are not symmetrical about a point. The method is carried out by using an apparatus having a supply station for supporting a stack of sheets in a vertical registration, a grinding station adjacent to the supply station having a grinding table rotatable about an upright grinding axis and adapted to support the sheets of glass during grinding, a template secured to the grinding table, and a pair of grinders in the grinding station radially engageable with the edges of the sheet on its grinding table and radially displaceable by the template. The method of the invention comprises the steps of transporting the sheets, one at a time from the stack in the supply station to the grinding station, simultaneously engaging the grinders with the sheet in the grinding station, while rotating this grinding table with its template and the sheet on the table through a 180.degree. to grind the edges of the sheet on the table, so that each such grinding operation displaces the template through 180.degree. about the axis. Finally, every other sheet is rotated while being transported from the supply station to the grinding station through 180.degree. about an intermediate vertical axis.
The U.S. Pat. No. 4,769,954 of Peter J. Hatas et al, refers to an apparatus for supporting and positioning a planar glass workpiece within a glass grinding apparatus. Three radially extended carriage assemblies are provided between a lower pan and an upper supporting platform. Each one of the carriage assembly extends radially outwardly from a central drive shaft connected to the supporting platform to the periphery of the lower pan. The radial inner ends of the carriage assemblies are rotatably supported about the drive shaft, while the radial outer ends are carried on respective motor assemblies connected to a gear formed on a lower pan. Energization of the motor assemblies causes the associated carriage assemblies to pivot relative to the lower pan. Each one of the carriage assemblies also carries a locator cylinder assembly thereon. The locator cylinder assemblies are movable radially, inwardly and outwardly throughout the length of the corresponding carriage assemblies by means of the associated motor assemblies. Each of the locator cylinder assemblies includes a locator button assembly. Each one of locator buttom assemblies is selectively movable between an extended position and a retracted position. A computer controls the operation of all of the motor assemblies so as to angularly position each of the carriage assemblies and to radially position each of the locator cylinder assemblies, all in accordance with predetermined stored data relating to the particular shape of the glass workpiece.
Notwithstanding the above, the present invention also is referred to an apparatus for finishing the edge of a sheet of glass, which is used to lubricate a grinding wheel and, simultaneously, collect the glass dust produced by the finishing operation on the edge of the glass sheet.
The apparatus for finishing the edge of a glass sheet is of the type that comprises a support structure, which includes a support base, a stationary vertical structure that is supported over the support base, and a supporting upper arm located in a horizontal position on the stationary vertical structure; a motor provided in a fixed manner at an end of the free supporting upper arm, said motor including a drive shaft supported in a vertical position for rotating over its own axis by the movement of the motor; a grinding wheel or a diamond wheel connected to the drive shaft to finish the edge of a glass sheet; and a tubular structure connected to the motor structure, which is positioned vertically in order to cover the drive shaft, the improvements are characterized by: a hollow housing for housing of the grinding wheel, said housing including: a first fixed section connected to the lower edge of the tubular structure, and a lower removable section, said lower removable section being meshed with the first fixed section through first a pivoting movement towards a closing position with respect to the first fixed section, and, for permitting the removal of said lower section when it is pivoted in an inverse position, a lateral slot in the lower removable section, for permitting the entry of the edge of the sheet of glass so as to make contact with the grinding wheel. A pair of continuous tubes for the distribution of a cooling fluid, which are placed by the internal periphery of the lower section of the housing for feeding the cooling fluid in the form of a mist, towards the edge and the upper and lower part of the grinding wheel. Means to cause a vacuum effect within the housing, for collecting a mixture of glass dust and water that is being generated within the housing during the finishing operation of the edge of the sheet of glass.